1. Field of the Invention
The present invention relates to an LCD driver for driving an LCD (liquid crystal display) in accordance with display data fed from a separately provided microcomputer, and particularly to an LCD driver for driving a dot-matrix LCD.
2. Description of the Prior Art
FIGS. 6A and 6B illustrate how a conventional LCD driver is used. As shown in FIG. 6A, a conventional LCD driver 73, when used in a portable phone or other appliance that incorporates a microcomputer 72 for controlling the entire appliance and an LCD 74, is placed between the microcomputer 72 and the LCD 74, so that the LCD driver 73, by being fed with display data from the microcomputer 72, drives the LCD 74.
Such an appliance is also provided with an nonvolatile data-storage device 71 such as an EEPROM (electrically erasable programmable read-only memory) for storing setting data so that a predetermined degree of contrast can be readily obtained in accordance with such factors as the type and use of the appliance. In the assembly process of the appliance, the contrast of the image displayed on the LCD 74 is adjusted to the desired degree, and the setting data for an electronic variable resistor at that time is stored in the data-storage device 71.
When this appliance is in actual use, the contrast of the LCD 74 is adjusted, as shown in FIG. 6B, by letting the microcomputer 72 read the setting data from the data-storage device 71 and feed it to the LCD driver 73. This helps prevent different LCDs 74 from exhibiting unduly different contrast as a result of variations in their characteristics that inevitably occur in their production.
However, storing the setting data for the electronic variable resistor in the data-storage device provided as a separate component requires the assembly process of the appliance such as a portable phone to include a step for adjusting the contrast of the display, that is, it necessitates an extra step in the assembly process. In addition, letting the microcomputer 72 read the setting data for the electronic variable resistor from the data-storage device 71 and feed it to the LCD driver 73 increases the operational burden to be borne by the microcomputer 72.